Process for pressing metal blanks



March 20, 1934. Q BUSSE 1,951,501

PROCESS FOR PREssING METAL BLANKS Filed Nov. 2, 1931 7 V/A Y/ hivan-14.*

orney.

Patented Mar. 20, 1934 UNITED STATES PATENT OFFICE Application November2, 1931, Serial No. 572,631 In Germany November 7, 1930 1 Claim.

This invention relates to a method of extruding metal blanks in the formof bars, wires, bands and tubes, more especially by the use of a plungerpress having a. matrix disposed in front of a hollow l plunger andpenetrating into the receiver.

The metal must be extruded at a temperature determined according to thenature of the alloy, which temperature must be maintained. If thetemperature of extrusion be too low the receiver l and the matrix areexposed to too great a stress and the structure and the mechanicalproperties-particularly the expansibility of the product and itscapacity for passing the notched bar testare prejudicially affected. Ifthe temperature of the blank is too high, the first part of the finalproduct is rendered useless by the presence of transverse fractures andbubbles, while the steel receiver loses its strength, widens in bore,and become useless. The best, alloyed and improved steel for thereceiver should not be heated theoretically to a temperature above 600C.-in practice a temperature of 500 C. is not exceededas the steel losesits temper at this temperature. The best known and most used alloy,consisting of 5,8 to 60% of copper, 2% of lead and the remainder of zincshould be extruded at a temperature which is not below 720 C.

According to the invention the blank is heated to different temperaturesfrom one endto the other, and is inserted into the receiver of the pressin such manner that the colder end is extruded before the warmer end.

The excess temperature of the rear end of the blank must be such thatthe material flowing through the matrix is at the moment at the correcttemperature for extrusion. The excess heat is transmitted to the matrix,the plunger and the receiver during the extrusion of the first part ofthe blank.

The accompanying drawing shows the known hydraulic press that is usuallyemployed and which is provided with main pressure cylinder 10, matrix11, hollow plunger 12 and receiver 13, with the blank to be extruded,which is conceived in this case as consisting of a. metal cylinder,lying between the operative parts of the press, that is to say, betweenthe main pressure cylinder 10 and the hollow plunger 12 provided withthe matrix 11. The receiver 13 is then pushed over the blank and theextrusion operation begins. In the case, .for example, of the alloyknown as Ms 58 the blank 1 to be extruded is according to the presentpractice introduced at a working temperature of '730 to r150 C. Incan'ying out the invention the 55 blank 1 is preheated at the forwardend 2 to from 730 to '150 C.that is, the usual temperaturewhile the rearend 3 is heated to a temperature of from about 800 to 320 C. Thisdiierence of temperature must, it will be understood, be selectedaccording to the nature of the alloy, the .30 rapidity of the extrusionoperation, and the dmensions of the operative parts of the press, andtherefore in accordance with the transference of heat from the blank tothe press.

An advantage of the invention is,-in addition 05 to the lengthening ofthe lift of the matrix and receiver, the saving in power and theobtaining of a perfect final product-an increase in the output of thepress to about double. This increase in output is due to the fact thatin the process according to the invention blanks of greater length andgreater cross-section than those that are handled by known methods ofproduction can be extruded.

The invention is not limited to the example hereinbefore described. Itmay be applied in similarly operated presses, for example, in plungerpresses in which the matrix is fixed in front of the receiver, and, insuch a press, particularly for the extrusion of tubes.

I claim:

A method of extruding metal blanks in the form of bars, wires, bands andtubes, by the use of a plunger press having a matrix disposed in frontof a hollow plunger, consisting in heating the B5 blank of the materialto be extruded so that one end of the blank is at a higher temperaturethan the other end and in inserting the blank into the receiver of thepress with the end at the higher temperature disposed farthest from thematrix, the said higher temperature being determined so that the metalat the far end of the blank is at approximately the correct temperaturefor extrusion when it is passing through the matrix.

OTTO BUSSE.

